Do airplane engine failures occur for unknown or mysterious reasons?

[N918KT]

Hello all. In light of recent events at CDW and on Long Island, I am wondering what exactly causes engine failures? I am not talking about running out of fuel or things that are at the pilot's fault or things that the pilot could prevent. If pilot error was not a cause or contributing factor, do engine failures occur for unknown or mysterious reasons or no reason at all?

I am no A&P mechanic and would like to learn more about what causes engine failures. If someone could explain them to me in layman's terms, that would be really great!

 

[SixPapaCharlie]

My friend heard this guy make a radio call that he was having engine trouble. He helped him navigate to a large field and land.

"Afterward, we drove out to look at the plane, most noticeable was the hole in the top of the cowling, after opening the oil access door you could see the big hole in the engine block, also you can see the connecting rod and piston pin laying on top of the cylinders, it also blew the Magneto completely off the engine. "

 

[eman1200]

My friend heard this guy make a radio call that he was having engine trouble. He helped him navigate to a large field and land.

"Afterward, we drove out to look at the plane, most noticeable was the hole in the top of the cowling, after opening the oil access door you could see the big hole in the engine block, also you can see the connecting rod and piston pin laying on top of the cylinders, it also blew the Magneto completely off the engine. "

Yeah, but why did the engine quit?

 

[Maciej]

Yeah, but why did the engine quit?

Looks like a connecting rod failed, windowed the block.

 

[wanttaja]

Hello all. In light of recent events at CDW and on Long Island, I am wondering what exactly causes engine failures? I am not talking about running out of fuel or things that are at the pilot's fault or things that the pilot could prevent. If pilot error was not a cause or contributing factor, do engine failures occur for unknown or mysterious reasons or no reason at all?

I am no A&P mechanic and would like to learn more about what causes engine failures. If someone could explain them to me in layman's terms, that would be really great!

Out of over 1500 Cessna 172 accidents, about 3.5% were due to a loss of engine power where the NTSB was unable to determine the cause. In some cases, the engine was damaged too severely to determine the cause. In others, the engine re-started after the accident.

In about 6.7% of the Cessna 172 accidents, some sort of mechanical problem occurred with the engine (some of these cases were due to mechanic error). This could include an internal engine difficulty (as is shown in previous posts), failures of the ignition or oil system, etc. Otherwise, about 1.5% of the accidents are due to carburetor ice, about 5.7% due to fuel exhaustion, etc.

Ron Wanttaja

 

[JHW]

The less you know about engines, the more mysterious are their problems. Get yourself an old $200 motorcycle, take the engine apart and put it back together. You'll learn plenty about engines that will stand you in good stead when you later have car or plane problems.

 

[Brad Z]

The less you know about engines, the more mysterious are their problems. Get yourself an old $200 motorcycle, take the engine apart and put it back together. You'll learn plenty about engines that will stand you in good stead when you later have car or plane problems.

...or a lawnmower, for that matter. Same idea.

 

[MAKG1]

There are a few failures that can leave no trace afterward. Carb ice being an example.

The rod failure above was likely the result of oil starvation or perhaps severe overheating. Both will leave evidence.

 

[44Gort]

(IMO) There are three Classes of Engine failures.

Operator Error
Maintenance induced
Internal Defect.

Operator errors include any operation that exceeds the manufacturers (both engine and Aircraft) recommendations. some AC have RPM limits and RPm bands where you are not allowed to operate. Prop imbalance can cause harmonic stress in the crankshaft/counterweight system and cause a crank failure. Likewise High Power settings and low airspeed can cause overheating.

Maintenance induced failures generally occur right after a significant maintenance activity, like an annual. Operations after an Oil Change should be watched carefully to observe any loss of oil pressure or overheating.

Internal Defects are the hardest to detect. They include defects in parts like connecting rods, valve guides/stems/seats/faces, spun bearings (which can be maintenance induced). A small nick in a forging can cause stress and lead to a failure.

Note that these "Classes" of failures are not the "Root Causes of Failures". That has to be determined after the fact.

 

[Jimmy cooper]

Include old engines. Old cranks, old cases , etc. Lots of reasons for it to fail from prop strike not logged to lousy mechanics, to lousy pilots over stressing ,on and on. Nothing very mysterious about an internal combustion engine. They've been around awhile.

 

[Sundancer]

I avoid too much engine knowledge, beyond what I can affect in flight. Tends to depress me. I helped someone rebuild a mag once, and after seeing all them little bitty parts, some of 'em plastic, I thought about boating, at least for a day or so.

If it isn't leaking anything on preflight, and seems secure in the mounts, I'm good; if it starts, and the needles stay in the green, and the noises are familiar, as well as the smells, I take off. Same-same in flight.

If you're in a 172, an engine failure won't kill you. Probaly not, anyway. Just fly all the way to "Stop"

Otherwise, don't worry, be happy.

 

[Dan Thomas]

I avoid too much engine knowledge, beyond what I can affect in flight. Tends to depress me. I helped someone rebuild a mag once, and after seeing all them little bitty parts, some of 'em plastic, I thought about boating, at least for a day or so.

Pretty hard to build a magneto, or any other ignition system, without using plastics. The alternative is metal, which tends to short everything and makes electricity impractical.

Your boat will have lots of plastic parts in it, too.

 

[X3 Skier]

Had a Cherokee eat a valve once. Apparently got chewed up and spit out thru a hole in the exhaust pipe. Within gliding distance of CVG and landed.

Cheers

 

[Sundancer]

Pretty hard to build a magneto, or any other ignition system, without using plastics. The alternative is metal, which tends to short everything and makes electricity impractical.

Your boat will have lots of plastic parts in it, too.

No boat, just thought about it. . .I'm good with non-conductors in electronics; just put off by them looking like a PlaySkool project, or Lego leftovers. Perception bias, I imagine.

But after doing a few magneto autopsies, I'm happy our airplane only has one.

 

[silver-eagle]

I have a Tahoe that keeps track of engine hours (tach time). It basically tells me that no matter how fast I've drove, my average mph is 28. Now I think a large % is highway, and even @ highway speeds a trip will average out to about 50. The major difference is an airplane engine will be running at a higher rpm for most of its life. The question is whether that is better or worse. My guess is airplane engines, like autos, will last as long equally if you take care of them properly.
My guess is more crashes are due to pilot error than mechanical, same, by the way, as auto accidents. Odd that we don't ntsb every auto accident. I am convinced many would be driver induced.

 

[Mason]

With about 5 hours SMOH, the engine on our 182 started running very rough shortly after takeoff from a 2000' grass strip at 500 AGL. I was aimed at the adjacent class C and talking to approach so I asked for a landing and was cleared. Made it the 4 miles, the engine quit totally on short final.

The balance tube, which is an intake pipe running between both cylinder banks, had fractured and the engine was sucking more air than fuel.

 

[SkyDog58]

With about 5 hours SMOH, the engine on our 182 started running very rough shortly after takeoff from a 2000' grass strip at 500 AGL. I was aimed at the adjacent class C and talking to approach so I asked for a landing and was cleared. Made it the 4 miles, the engine quit totally on short final.

The balance tube, which is an intake pipe running between both cylinder banks, had fractured and the engine was sucking more air than fuel.

That literally sucked. Glad to hear you made it ok.

 

[MAKG1]

I have a Tahoe that keeps track of engine hours (tach time). It basically tells me that no matter how fast I've drove, my average mph is 28. Now I think a large % is highway, and even @ highway speeds a trip will average out to about 50. The major difference is an airplane engine will be running at a higher rpm for most of its life. The question is whether that is better or worse. My guess is airplane engines, like autos, will last as long equally if you take care of them properly.
My guess is more crashes are due to pilot error than mechanical, same, by the way, as auto accidents. Odd that we don't ntsb every auto accident. I am convinced many would be driver induced.

I think you'll find that the cruise RPM on your Tahoe, and the cruise RPM on your airplane, are rather similar. The difference is that your Tahoe is capable of much higher RPM due to much shorter connecting rods. Most modern car/light truck engines run their best at 2000-2500 RPM. OHCs may be even faster. They idle much lower because the power is not being used -- then, it's just fast enough to keep it running. But stomping the throttle that low with a positive clutch (stick) is going to result in unpleasant sounds and not much acceleration.